4847123
| Frage | Antworten |
| How would you change this to a relational schema? | |
| Translate to a relational model | |
| Translate to relational model | |
| Translate using 3 relations | |
| Translate using 3 relations | |
| What should you do when you have: Entity type -> Relation. | Choose an identifier as primary key. |
| What should you do when you have: Weak entity type -> Relation. | Use the weak identifier + the identifier of the identifying entity type as primary key. |
| What should you do when you have: One-to-many relationship | 1.Foreign key (i.e., additional attribute/column). 2. Relation, two foreign keys, primary key of the entity to the N side. |
| What should you do when you have: Many-to-many relationship | Relation, two foreign keys, primary key of the entity to the N side, but both foreign keys form the primary key. |
| ER to relational: Entity type | Entity relation |
| ER to relational: 1:1 or 1:N relationship type | Foreign key (or relationship relation) |
| ER to relational: M:N relationship type | Relationship relation and two foreign keys |
| ER to relational: n-ary relationship type | Relationship relation and n foreign keys |
| ER to relational: Simpel attribute | Attribute |
| ER to relational: Composite attribute | Set of simple component attributes |
| ER to relational: Multivalued attribute | Relation and foreign key |
| ER to relational: Value set | Domain |
| ER to relational: Key attribute | Primary (or secondary) key |
| What 3 elements defines a trigger? | – EVENT – CONDITION – ACTION |
Möchten Sie mit GoConqr kostenlos Ihre eigenen Karteikarten erstellen? Mehr erfahren.